The present invention relates to lighting devices, for example ones used in residential, commercial and industrial environments, of the kind comprising at least one fluorescent light source of a linear type, which extends longitudinally between a reflector that is formed by an elongated body having a curved surface, and a set of transverse fins, which are set at a distance apart from one another and which define a grill for directional control of the light emitted by the light source.
Light sources of the above sort consist, in practice, of a reflecting optical system designed to control the direction of the outcoming light, guaranteeing limits of luminance below dazzling.
With lighting devices of this kind, control of luminance proves problematical in the case of particularly extensive fluorescent light sources. In fact, with the embodiments currently produced and marketed, in which the transverse fins are generally made up of simple extruded metallic elements having a parabolic profile in the direction perpendicular to the direction of extrusion, angular control of the outcoming light is effective only in the planes that are, respectively, perpendicular and parallel to the axis of the lamp. In the remaining directions, this control is normally ineffective, and, in any case, insufficient.
The purpose of the present invention is precisely to solve the above problem and to provide a lighting device of the type defined above, which is designed to enable control of the luminance in all directions.
According to the invention, the above purpose is achieved basically thanks to the fact that, in a lighting device of the type defined at the beginning of this description, the reflector defines, together with said transverse fins, a plurality of elements set alongside one another having a generally parabolic shape. The curved surface of the elongated body 1 is curved in a longitudinal direction of the elongated body and transversely with respect to each transverse fin 3.
Each of said elements set alongside one another conveniently has a bottom wall formed with a cusp in a position corresponding to the light source.
According to a preferred embodiment of the invention, the reflector is made up of two separable units, one of which includes said fins and the other includes the bottom walls of said elements set alongside one another. Each transverse fin 3 is provided with e double curvature both with respect to a longitudinal plane and a transverse plane perpendicular to the light source 5 as best seen in FIGS. 1 and 4.